Tetramethylpyrazine combined with aminoguanidine improves renal functions in n0-STZ Wistar rats

AIM: To investigate the effects of tetramethylpyrazine combined with aminoguanidine on the renal functions of neonatal-0 streptozotocin-induced (n0-STZ) rats. METHODS: Neonatal Wistar rats were intraperitoneally injected with a single dose of streptozotocin (STZ) to establish the n0-STZ rat model. The n0-STZ rats were divided into 4 groups: normal control group, insulin resistance group, metformin treatment group and tetramethylpyrazine+aminoguanidine treatment group. Fasting plasm glucose, fasting insulin, insulin resistance index, blood urea nitrogen, serum creatinine, urine albumin and glomerular filtration rate were measured at the 32nd week. The mRNA content of inducible nitric oxide synthase (iNOS) in peripheral blood leukocytes was detected by the technique of in situ hybridization. Nitric oxide (NO) concentration, iNOS activity, the protein expression of iNOS and 3-nitrotyrosine(3-NT) were also assessed in the renal tissues. RESULTS: At the 8th week after the administration of STZ, 82.5% of Wistar rats showed that the fasting plasm glucose level was ≥7.0 mmol/L and the renal functions were seriously damaged. Although both metformin and the combined treatment reduced fasting plasm glucose, fasting insulin and insulin resistance index, the combined treatment was superior in improving the insulin resistance. The damaged renal functions were improved by the combined treatment as reducing blood urea nitrogen and creatinine, increasing glomerular filtration rate were observed. Furthermore, the combined treatment reduced NO concentration, decreased iNOS activity and diminished mRNA content of iNOS, resulting in depressing the generation of 3-NT and iNOS, which surpassed the treatment of metformin. CONCLUSION: Tetramethylpyrazine combined with aminoguanidine improves the renal functions of n0-STZ rats by depressing nitrative stress and enhancing the effect of metformin.